Reference

All functions
london_a() london_c()	Region representing London in projected coordinate system
zb_100_triangular_numbers	The first 100 triangular numbers
zb_color()	Generate colors for zones
zb_doughnut()	Make doughnuts
zb_lines()	Create lines radiating at equal angles from a point
zb_plot()	Plot zones
zb_quadrat()	Divide a region into quadrats
zb_segment()	Make segments
zb_view()	View zones
zb_zone()	Generate zones covering a region of interest